As a critical candidate technology for the fifth generation mobile communication technology (5G), D2D communication has potential prospects of improving system performance, improving user experience, and extending cellular communications applications and has received wide attention. D2D communication based on a cellular network (or referred to as proximity service (ProSe)) means that user data can be directly transmitted between terminal devices without being relayed by a network.
One of the development targets of mobile communication is to establish an extensive interconnected network that comprises various types of terminals, which is also one of the purposes of developing the Internet of Things inside the framework of a cellular communication currently. According to the prediction of the industry, by the year 2020, globally there will be about 50 billion cellular access terminals, most of which will be machine communication terminals that have Internet of Things features. By means of the combination of a D2D technology and the Internet of Things, an interconnected wireless communication network of real significance may appear.